需要匯入excel相應的jar包

form表單需要加上enctype=”multipart/form-data”這個屬性

    //封裝上傳檔案物件
    private File userExcel;
    // 封裝上傳檔案型別的屬性
    private String userExcelContentType;
    // 封裝上傳檔名的屬性
    private String userExcelFileName;

action中所需的欄位

action下載的方法

public String exportExcel() throws IOException{
        //1.查詢使用者
 

        List<User> userlist = userService.findObjects();
        //2.匯出excel
        HttpServletResponse response = ServletActionContext.getResponse();
        response.setContentType("application/x-execl");
        response.setHeader("Content-Disposition", "attachment;filename=" + new String("使用者列表.xls"
 
.getBytes(), "ISO-8859-1"));
        ServletOutputStream outputStream = response.getOutputStream();

        try {
            userService.exportExcel(userlist,outputStream);    //封裝的工具類
        } catch (Exception e) {
            e.printStackTrace();
        }

        if(outputStream!=null){
            outputStream.close();
        }

        return
 
 null;
    }

工具類

public class ExcelUtil {
    public static void exportExcelUsers(List<User> userlist,ServletOutputStream outputStream) throws Exception{
        //1.建立工作薄
        HSSFWorkbook workbook = new HSSFWorkbook();

        // 1.1建立合併單元格
        CellRangeAddress cra = new CellRangeAddress(0, 0, 0, 6);

        // 1.2建立標題樣式
        CellStyle style1 = createStyle(workbook, 16);
        // 1.3建立列標題樣式
        CellStyle style2 = createStyle(workbook, 12);
        // 2.建立工作表
        Sheet sheet = workbook.createSheet("hello world");
        // 設定預設列寬
        sheet.setDefaultColumnWidth(15);
        // 2.1將合併單元格作用於sheet
        sheet.addMergedRegion(cra);
        // 3.建立行
        Row row = sheet.createRow(0);
        // 4.建立單元格
        Cell cell = row.createCell(0);
        // 5.向單元格寫入資料
        cell.setCellValue("使用者列表");
        // 6.將單元格加入樣式
        cell.setCellStyle(style1);

        // 寫列標題
        String[] titles = { "使用者名稱", "帳號", "所屬部門", "性別", "手機號碼", "電子郵箱", "生日" };
        // 建立列標題行
        Row row2 = sheet.createRow(1);
        for (int i = 0; i < titles.length; i++) {
            // 建立單元格
            Cell cell1 = row2.createCell(i);
            // 向單元格寫入資料
            cell1.setCellValue(titles[i]);
            // 將單元格加入樣式
            cell1.setCellStyle(style2);
        }

        for (int i = 0; i < userlist.size(); i++) {
            User user = userlist.get(i);
            Row rowdata = sheet.createRow(i + 2);
            // 姓名
            Cell cell0 = rowdata.createCell(0);
            cell0.setCellValue(user.getName());
            // 賬號
            Cell cell1 = rowdata.createCell(1);
            cell1.setCellValue(user.getAccount());
            // 部門
            Cell cell2 = rowdata.createCell(2);
            cell2.setCellValue(user.getDept());
            // 性別
            Cell cell3 = rowdata.createCell(3);
            cell3.setCellValue(user.isGender() ? "男" : "女");
            // 手機
            Cell cell4 = rowdata.createCell(4);
            cell4.setCellValue(user.getMobile());
            // 電郵
            Cell cell5 = rowdata.createCell(5);
            cell5.setCellValue(user.getEmail());
            // 生日
            Cell cell6 = rowdata.createCell(6);
            if(user.getBirthday()!=null){
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
                cell6.setCellValue(sdf.format(user.getBirthday()));
            }else{
                cell6.setCellValue("");
            }


        }

        // 6.寫入硬碟檔案
        workbook.write(outputStream);
        workbook.close();
    }


//設定樣式方法
    public static CellStyle createStyle(Workbook workbook,int fontsize){
        //1.2設定單元格樣式
        CellStyle style = workbook.createCellStyle();
        // 設定水平居中
        style.setAlignment(CellStyle.ALIGN_CENTER);
        // 設定垂直居中
        style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
        // 1.3設定字型
        Font font = workbook.createFont();
        // 設定字型為ARIAL
        font.setFontName(HSSFFont.FONT_ARIAL);
        // 設定粗體
        font.setBoldweight(Font.BOLDWEIGHT_BOLD);
        // 設定字型顏色
        //font.setColor(HSSFColor.BLUE.index);
        // 設定字型大小
        font.setFontHeightInPoints((short) fontsize);
        // 將字型加入樣式
        style.setFont(font);
        return style;
    }

excel上傳方法

public String importExcel(){
        //先判斷上傳的檔案是不是excel  
        if(userExcelFileName.matches("^.+\\.(?i)(xls|xlsx)$")){
            try {
                userService.importExcel(userExcel,userExcelFileName);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return "list";
    }


//dervice中的方法
public void importExcel(File userExcel, String userExcelFileName) throws Exception {
        FileInputStream fis = new FileInputStream(userExcel);
        boolean b = userExcelFileName.matches("^.+\\.xlsx$");
        //1.建立工作薄
                Workbook workbook = null;
                workbook=b?new XSSFWorkbook(fis):new HSSFWorkbook(fis);
                //2.獲取工作表
                Sheet sheet = workbook.getSheetAt(0);
                int nums = sheet.getPhysicalNumberOfRows();
                System.out.println(nums);
                if(nums>2){
                    User user = null;
                    for(int i=2;i<nums;i++){
                        user = new User();
                        Row row = sheet.getRow(i);
                        //4.獲取單元格
                        Cell namecell = row.getCell(0);
                        String name = namecell.getStringCellValue();
                        user.setName(name);

                        Cell accountcell = row.getCell(1);
                        String account = accountcell.getStringCellValue();
                        user.setAccount(account);

                        Cell deptcell = row.getCell(2);
                        String dept = deptcell.getStringCellValue();
                        user.setDept(dept);

                        Cell gendercell = row.getCell(3);
                        String gender = gendercell.getStringCellValue();
                        user.setGender(gender.equals("男"));

                        Cell mobilecell = row.getCell(4);
                        String mobile = null;
                        try {
                            mobile = mobilecell.getStringCellValue();
                        } catch (Exception e) {
                            mobile = BigDecimal.valueOf(mobilecell.getNumericCellValue()).toString();
                        }
                        user.setMobile(mobile);

                        Cell emailcell = row.getCell(5);
                        String email = emailcell.getStringCellValue();
                        user.setEmail(email);

                        Cell birthdaycell = row.getCell(6);
                        String birthday = birthdaycell.getStringCellValue();
                        if(birthday!=null){
                            SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
                            user.setBirthday(sdf.parse(birthday));
                        }

                        //設定使用者狀態
                        user.setState(User.USER_STATE_VALID);
                        //設定使用者預設密碼
                        user.setPassword("123456");

                        userDao.save(user);

                    }
                }
    }